Substrate conveying robot and operation method therefor

ABSTRACT

A substrate conveying robot has a robot arm including an end effector having a substrate holding unit holding a substrate, arm drive unit for driving the robot arm, an elevating drive unit for elevatingly driving the end effector, a robot control unit controlling the arm drive unit, the elevating drive unit, and the substrate holding unit, and a substrate detection unit having a substrate detection unit which detects a vertical position of the substrate and elevates coordinately with an elevating operation of the end effector. By this configuration, a vertical position of a substrate to be conveyed is detected with high accuracy so that a robot operation can be controlled based on the detection result.

This application is a continuation of U.S. patent application Ser. No.15/550,832, filed Aug. 14, 2017, which is a national stage entry ofPCT/JP2015/053970, filed Feb. 13, 2015. The disclosures of each of theabove are hereinafter incorporated by reference in their entireties.

TECHNICAL FIELD

The present invention relates to a substrate conveying robot comprisinga robot arm to which an end effector having a substrate holding unit forholding a substrate is provided and its operation method.

BACKGROUND ART

Conventionally, a substrate conveying robot is used as a means forconveying a substrate such as a semiconductor wafer. The substrateconveying robot comprises an articulated robot arm and an end effector(hand) provided to a tip end of the robot arm, for example.

Usually, a plurality of wafers are stored in a substrate storingcontainer such as a FOUP (wafer cassette). The substrate conveying robottakes a wafer to be conveyed from the inside of the substrate storingcontainer and conveys the same to the side of a treatment apparatus fortreating the wafer. Or, it takes a treated wafer from a wafer holder onthe treatment apparatus side and stores the same inside the substratestoring container.

When taking a wafer from the substrate storing container or the waferholder using the substrate conveying robot, the operation of the robotarm is controlled by a robot controller so as to insert the end effectorinto an interval between wafers in the vertical direction. From thisstate, the end effector is elevated so as to place a wafer to beconveyed on the end effector, and the wafer is fixed on the end effectorby a substrate holding unit.

A heat treatment film forming apparatus used in a thermal process, forexample, is given as a treatment apparatus for treating a wafer. In theheat treatment film forming apparatus, a plurality of wafers are loadedon a wafer holder configured in a multistage and the plurality of wafersare treated at the same time by a batch treatment.

In the heat treatment film forming apparatus mentioned above, asubstrate pitch in the vertical direction in the wafer holder needs tobe small in order to increase the number of treated wafers by the batchtreatment. Also in the substrate storing container, a substrate pitch inthe vertical direction in the container needs to be small in order toenhance the storing sufficiency.

As above, when a substrate pitch in the vertical direction becomessmall, a position accuracy required for the robot operation wheninserting the end effector of the substrate conveying robot into aninterval between wafers increases.

Conventionally, a worker has performed a teaching operation (teaching)on the substrate conveying operation while confirming positions of theend effector and the wafer by sight. Therefore, much effort and timehave been required for the teaching operation on the substrate conveyingoperation.

Note that, as a means for detecting a storing state of a plurality ofwafers inside the substrate storing container, a means of scanning edgeportions of a plurality of wafers using an optical sensor provided tothe end effector is known. This is called mapping which can determinethe presence or absence of a wafer inside the substrate storingcontainer prior to the substrate conveying process by the substrateconveying robot.

CITATION LIST Patent Document

[Patent Document 1] Japanese Patent Application Laid-Open No.2000-124289

SUMMARY OF INVENTION Objects to be Achieved by the Invention

However, the optical sensor provided to the end effector is fordetermining the presence or absence of a wafer inside the substratestoring container as stated above, and it is not for detecting avertical position of a wafer. Since a mounting error of the opticalsensor to the end effector occurs usually, even when a vertical positionof a wafer is detected, ensuring a sufficient accuracy for detecting theposition is extremely difficult or impossible.

The present invention is made considering the above-stated problems ofthe conventional technique, and its object is to provide a substrateconveying robot capable of detecting a vertical position of a substrateto be conveyed with high accuracy and controlling the robot operationbased on the detection result, and its operation method.

Means for Achieving the Objects

In order to achieve the above-stated objects, a substrate conveyingrobot according to a first aspect of the present invention comprises arobot arm including an end effector having a substrate holding unit forholding a substrate, an arm drive unit for driving the robot arm, anelevating drive unit for elevatingly driving the end effector, a robotcontrol unit for controlling the arm drive unit, the elevating driveunit, and the substrate holding unit, and a substrate detection unit fordetecting a vertical position of the substrate, wherein the substratedetection unit has a substrate detection sensor elevating coordinatelywith an elevating operation of the end effector.

A second aspect of the invention is that, in the first aspect, the robotcontrol unit is configured to control the elevating drive unit forraising or lowering the end effector so as to detect the substrate bythe substrate detection sensor and specify a separation distance betweena reference surface of the end effector and the substrate detectionsensor in a vertical direction based on a vertical position of the endeffector at its detection time point and a vertical position of the endeffector at a time point when the substrate is held by the substrateholding unit at a normal substrate holding position.

A third aspect of the invention is that, in the first or second aspect,the reference surface of the end effector is matched with the normalsubstrate holding position.

A fourth aspect of the invention is that, in any one of the first tothird aspects, a holding state determination unit for determiningwhether the substrate is held by the substrate holding unit or not isfurther provided.

A fifth aspect of the invention is that, in the fourth aspect, the robotcontrol unit is configured so as to detect a time point when adetermination result of the holding state determination unit is switchedwhile raising or lowering the end effector by the elevating drive unitby a predetermined distance in order to detect a vertical position ofthe end effector at a time point when the substrate is held by thesubstrate holding unit at the normal substrate holding position.

A sixth aspect of the invention is that, in the fourth or fifth aspects,the substrate holding unit has a movable engagement portion engaged withan edge portion of the substrate releasably and a plunger for drivingthe movable engagement portion, and the holding state determination unithas a position sensor for detecting a position of the plunger.

A seventh aspect of the invention is that, in the fourth or fifthaspect, the substrate holding unit has a vacuum suction unit for vacuumsucking the substrate, and the holding state determination unit has avacuum sensor which detects that a vacuum state is achieved by thevacuum suction unit.

An eighth aspect of the invention is that, in any one of the first toseventh aspects, the substrate detection sensor is provided in the endeffector.

A ninth aspect of the invention is that, in any one of the first toeighth aspects, the end effector is configured so as to be elevatedintegrally with the robot arm, and the elevating drive unit isconfigured so as to elevate the end effector by elevating the robot arm.

A tenth aspect of the invention is that, in any one of the first toninth aspects, the robot control unit is configured so as to detect avertical position of the substrate to be conveyed by the substratedetection sensor and control the elevating drive unit based on adetection result so as to hold the substrate by the substrate holdingunit.

In order to achieve the above-mentioned objects, an eleventh aspect ofthe present invention is an operation method of a substrate conveyingrobot comprising a robot arm to which an end effector having a substrateholding unit for holding a substrate is provided, comprising a detectionobject substrate detection process detecting the substrate to bedetected using a substrate detection sensor elevating integrally with anelevating operation of the end effector, an end effector positiondetection process detecting a vertical position of the end effector at atime point when the substrate to be detected is held at a normalsubstrate holding position by the substrate holding unit, and aseparation distance specifying process specifying a separation distancebetween the reference surface of the end effector and the substratedetection sensor in a vertical direction based on a detection result inthe detection object substrate detection process and a detection resultin the end effector position detection process.

A twelfth aspect of the invention is that, in the eleventh aspect, thesubstrate conveying robot further has a holding state determination unitfor determining whether the substrate is held by the substrate holdingunit or not, detecting a time point when a determination result of theholding state determination unit is switched while raising or loweringthe end effector by a predetermined distance in the end effectorposition detection process.

A thirteenth aspect of the invention is that, in the twelfth aspect, thesubstrate to be detected is displaced from the normal substrate holdingposition at a time point when a determination result of the holdingstate determination unit is switched.

A fourteenth aspect of the present invention is that, in the twelfthaspect, the substrate to be detected is at the normal substrate holdingposition at a time point when a determination result of the holdingstate determination unit is switched.

A fifteenth aspect of the invention is that, in any one of the eleventhto fourteenth aspects, the reference surface of the end effector ismatched with the normal substrate holding position.

A sixteenth aspect of the invention is that, in any one of the eleventhto fifteenth aspects, a conveying object substrate position detectionprocess detecting a vertical position of the substrate to be conveyedusing the substrate detection sensor based on the separation distanceobtained in the separation distance specifying process is furtherprovided.

Effect of the Invention

According to the present invention, a substrate conveying robot capableof detecting a vertical position of a substrate to be conveyed with highaccuracy and controlling the robot operation based on the detectionresult and its operation method can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view schematically illustrating a substrateconveying robot according to an embodiment of the present invention.

FIG. 2 is an enlarged side view schematically illustrating a part of theend effector of the substrate conveying robot in FIG. 1 .

FIG. 3 is an enlarged plan view schematically illustrating the part ofthe end effector of the substrate conveying robot in FIG. 1 .

FIG. 4 is a schematic cross-section view illustrating a method fordetecting a substrate using the substrate conveying robot in FIG. 1 .

FIG. 5 is a schematic longitudinal section view illustrating the methodfor detecting a substrate using the substrate conveying robot in FIG. 1.

FIG. 6 is a schematic enlarged view illustrating a method for specifyinga separation distance between the reference surface of the end effectorand a substrate detection sensor in the vertical direction using thesubstrate conveying robot in FIG. 1 .

FIG. 7 is another schematic enlarged view illustrating a method forspecifying a separation distance between the reference surface of theend effector and the substrate detection sensor in the verticaldirection using the substrate conveying robot in FIG. 1 .

FIG. 8 is another schematic enlarged view illustrating a method forspecifying a separation distance between the reference surface of theend effector and the substrate detection sensor in the verticaldirection using the substrate conveying robot in FIG. 1 .

FIG. 9 is a schematic enlarged view illustrating a method for detectinga vertical position of the end effector at a time point when a substrateto be detected is held by a substrate holding unit using the substrateconveying robot illustrated in FIG. 1 .

FIG. 10 is another schematic enlarged view illustrating a method fordetecting a vertical position of the end effector at a time point when asubstrate to be detected is held by the substrate holding unit using thesubstrate conveying robot illustrated in FIG. 1 .

FIG. 11 is another schematic enlarged view illustrating a method fordetecting a vertical position of the end effector at a time point when asubstrate to be detected is held by the substrate holding unit using thesubstrate conveying robot illustrated in FIG. 1 .

FIG. 12 is another schematic enlarged view illustrating a method fordetecting a vertical position of the end effector at a time point when asubstrate to be detected is held by the substrate holding unit using thesubstrate conveying robot illustrated in FIG. 1 .

FIG. 13 is another schematic enlarged view illustrating a method fordetecting a vertical position of the end effector at a time point when asubstrate to be detected is held by the substrate holding unit using thesubstrate conveying robot illustrated in FIG. 1 .

FIG. 14 is another schematic enlarged view illustrating a method fordetecting a vertical position of the end effector at a time point when asubstrate to be detected is held by the substrate holding unit using thesubstrate conveying robot illustrated in FIG. 1 .

FIG. 15 is another schematic enlarged view illustrating a method fordetecting a vertical position of the end effector at a time point when asubstrate to be detected is held by the substrate holding unit using thesubstrate conveying robot illustrated in FIG. 1 .

FIG. 16 is another schematic enlarged view illustrating a method fordetecting a vertical position of the end effector at a time point when asubstrate to be detected is held by the substrate holding unit using thesubstrate conveying robot illustrated in FIG. 1 .

FIG. 17 is another schematic enlarged view illustrating a method fordetecting a vertical position of the end effector at a time point when asubstrate to be detected is held by the substrate holding unit using thesubstrate conveying robot illustrated in FIG. 1 .

FIG. 18 is another schematic enlarged view illustrating a method fordetecting a vertical position of the end effector at a time point when asubstrate to be detected is held by the substrate holding unit using thesubstrate conveying robot illustrated in FIG. 1 .

FIG. 19 is an enlarged view schematically illustrating a substrateholding unit according to a variation of the substrate conveying robotillustrated in FIG. 1 .

FIG. 20 is a schematic enlarged view illustrating a method forspecifying a separation distance between the reference surface of theend effector and the substrate detection sensor in the verticaldirection using the substrate conveying robot illustrated in FIG. 19 .

FIG. 21 is another schematic enlarged view illustrating a method forspecifying a separation distance between the reference surface of theend effector and the substrate detection sensor in the verticaldirection using the substrate conveying robot illustrated in FIG. 19 .

FIG. 22 is a schematic enlarged view illustrating a method for detectinga vertical position of the end effector at a time point when a substrateto be detected is held by the substrate holding unit using the substrateconveying robot illustrated in FIG. 19 .

FIG. 23 is another schematic enlarged view illustrating a method fordetecting a vertical position of the end effector at a time point when asubstrate to be detected is held by the substrate holding unit using thesubstrate conveying robot illustrated in FIG. 19 .

FIG. 24 is another schematic enlarged view illustrating a method fordetecting a vertical position of the end effector at a time point when asubstrate to be detected is held by the substrate holding unit using thesubstrate conveying robot illustrated in FIG. 19 .

FIG. 25 is a perspective view schematically illustrating anothervariation of the substrate conveying robot illustrated in FIG. 1 .

FIG. 26 is an enlarged perspective view illustrating a part of the endeffector of the substrate conveying robot illustrated in FIG. 25 .

EMBODIMENT OF THE INVENTION

Hereunder, a substrate conveying robot according to an embodiment of thepresent invention will be described referring to the figures. Note thatthe substrate conveying robot according to the embodiment isparticularly suitable for conveying a wafer for manufacturing asemiconductor.

As illustrated in FIG. 1 , a substrate conveying robot 1 according tothe embodiment has a base 2. A rotary spindle 3 is provided on the base2 so as to elevate along a first rotational axis line L1.

The base end of a robot arm 4 is connected on the upper end of therotary spindle 3. The robot arm 4 has a first link member 5 having thefirst rotational axis line L1 on the base end thereof and also having asecond rotational axis line L2 on the tip end thereof, and a second linkmember 6 having the second rotational axis line L2 on the base endthereof and also having a third rotational axis line L3 on the tip endthereof. An end effector (hand) 7 is provided on the tip end of thesecond link member 6 so as to rotate about the third rotational axisline L3.

The elevating operation and the rotating operation of the rotary spindle3 are performed by drive sources 8, 9 provided inside the base 2respectively. The rotary spindle 3 rotates about the first rotationalaxis line L1 so that the first link member 5 rotates about the firstrotational axis line L1 integrally with the rotary spindle 3.

The rotational operation of the second link member 6 with respect to thefirst link member 5 is performed by a drive source 10 provided insidethe first link member 5. The rotating operation of the end effector 7with respect to the second link member 6 is performed by a drive source11 provided inside the second link member 6.

The above-stated drive source 8 configures an elevating drive unit inthe present invention. The above-stated drive sources 9, 10, 11configure an arm drive unit in the present invention. The drive sources8, 9, 10, 11 can be configured by servo motors, for example.

Each drive source 8, 9, 10, 11 is controlled by a robot controller 12.Thereby, the elevating operation and the rotating operation of the robotarm 4 having the end effector 7 are controlled.

Note that a configuration of a robot arm of the substrate conveyingrobot according to the present invention and its drive unit is notlimited to the configuration above as illustrated in FIG. 1 , and anyconfiguration capable of positioning an end effector to a substrate tobe conveyed can be employed.

As illustrated in FIG. 2 and FIG. 3 , the substrate conveying robot 1according to the embodiment comprises a substrate holding unit 13 forholding a substrate S on the end effector 7 thereof. The substrateholding unit 13 has a fixed engagement portion 14 engaged with an edgeportion on the front side of the substrate S, a movable engagementportion 15 engaged releasably with an edge portion on the rear side ofthe substrate S, and a plunger 16 for driving the movable engagementportion 15 advancingly and retreatingly.

The fixed engagement portion 14 is provided to each of the tip endportions of the end effector 7 in a bifurcated shape. The movableengagement portion 15 is provided to each of both end portions of aslender member 17 extending in the direction orthogonal to thelongitudinal axis line of the end effector 7 on the base end side of theend effector 7.

As illustrated in FIG. 2 , a step portion 18 is formed in the fixedengagement portion 14, and the substrate S is placed on the step portion18. In the example, a horizontal surface including the step portion 18of the fixed engagement portion 14 is a reference surface P0 of the endeffector 7. In the example, the lower surface of the substrate S held ina normal holding position of the end effector 7 is matched with thereference surface P0 of the end effector 7.

In the substrate conveying robot 1 according the embodiment, a holdingstate and a non-holding state of the substrate S on the end effector 7can be switched therebetween by driving the plunger 16 advancingly andretreatingly by the robot controller 12.

As illustrated in FIG. 3 , a position sensor (holding statedetermination unit) 19 for detecting a position of the plunger 16 isprovided adjacent to the plunger 16. Whether the substrate S is held onthe end effector 7 or not can be determined by the position sensor 19.

Further, the substrate conveying robot 1 according to the embodimentcomprises a substrate detection sensor (substrate detection unit) 20 fordetecting a vertical position of the substrate S. The substratedetection sensor 20 is an optical sensor provided inside the tip endportion of the end effector 7 in a bifurcated shape, and the opticalsensor is a transmission type sensor having a light emitting portion anda light receiving portion. The light emitting portion of the opticalsensor is provided to one tip end portion of the end effector 7 in abifurcated shape, and the light receiving portion of the optical sensoris provided to the other tip end portion of the end effector 7 in abifurcated shape.

When detecting the substrate S, a light is emitted from the lightemitting portion of the optical sensor configuring the substratedetection sensor 20 toward the light receiving portion of the opticalsensor. Then, if the substrate S does not exist on the way of theoptical path, the light emitted from the light emitting portion is madeincident on the light receiving portion and an output signal of theoptical sensor is turned on. On the other hand, when the substrate Sexists on the way of the optical path, the light emitted from the lightemitting portion is interrupted by the substrate S, not reaching thelight receiving portion, and the output signal of the optical sensor isturned off.

Note that, as a variation, a configuration that both the light emittingportion and the light receiving portion of the optical sensor areprovided to one tip end portion of the end effector 7 in a bifurcatedshape and a reflector is provided to the other tip end portion of theend effector 7 in a bifurcated shape can also be employed. In theconfiguration, if the substrate S does not exist on the optical path,the light emitted from the light emitting portion of the optical sensoris reflected by the reflector and reaches the light receiving portion ofthe optical sensor.

When detecting a vertical position of the substrate S supported by asubstrate supporting portion 22 of a substrate storing container 21 suchas a FOUP using the substrate detecting sensor 20, the elevating driveunit 8 and the arm drive unit 9, 10, 11 are driven by the robotcontroller 12 so that the end effector 7 is raised or lowered in thestate that an edge portion of the substrate S is positioned between theleft and right tip end portions of the end effector 7 as illustrated inFIG. 4 and FIG. 5 .

Further, in the substrate conveying robot 1 according to the embodiment,a separation distance between the reference surface P0 of the endeffector 7 and the substrate detection sensor 20 in the verticaldirection is specified, and a vertical position of the substrate S canbe detected by the above-described method based on the specifiedseparation distance.

Hereunder, a method for specifying the separation distance between thereference surface P0 of the end effector 7 and the substrate detectionsensor 20 in the vertical direction will be described.

As illustrated in FIG. 6 , the separation distance between the referencesurface P0 of the end effector 7 and the substrate detection sensor 20in the vertical direction is D1. Here, there is an error in a mountingposition of the substrate detection sensor 20 to the end effector 7.Therefore, a mounting position of the substrate detection sensor 20 hasindividual difference for each end effector 7. Therefore, theabove-stated separation distance D1 needs to be specified in order toaccurately detect a vertical position of the substrate S using thesubstrate detection sensor 20 of the substrate conveying robot 1.

Then, in the substrate conveying robot 1 according to the embodiment,first, the lower surface of the substrate S to be detected supported bythe substrate supporting portion 22 of the substrate storing container21 such as the FOUP is detected using the substrate detection sensor 20provided in the end effector 7 as illustrated in FIG. 7 (detectionobject substrate detection process). Also, a vertical position of theend effector 7 at a time point when the substrate S to be detected isheld by the substrate holding unit 13 is detected (end effector positiondetection process).

In the end effector position detection process, the end effector 7 iselevatingly driven so that a vertical position of the lower surface ofthe substrate S is substantially matched with a position of an uppersurface 14A of the fixed engagement portion 14 of the end effector 7 asillustrated in FIG. 8 .

The end effector 7 needs to be lowered by a distance D3 from the stateillustrated in FIG. 7 in order to make the state illustrated in FIG. 7 ,namely the state that the lower surface of the substrate S is detectedby the substrate detection sensor 20 into the state illustrated in FIG.8 , namely the state that the lower surface of the substrate S issubstantially matched with the upper surface 14A of the fixed engagementportion 14 of the end effector 7. The distance D3 is a separationdistance between the upper surface 14A of the fixed engagement portion14 and the substrate detection sensor 20 in the vertical direction.

Here, a distance D2 between the upper surface 14A of the fixedengagement portion 14 of the end effector 7 and the reference surface P0of the end effector 7 in the vertical direction is previously known as amachining dimension. Accordingly, if the distance D3 can be identified,the separation distance D1 between the reference surface P0 of the endeffector 7 and the substrate detection sensor 20 in the verticaldirection can be specified by subtracting the known distance D2 from thedistance D3.

The distance D3 illustrated in FIG. 6 and FIG. 8 , namely the distanceD3 between the upper surface 14A of the fixed engagement portion 14 andthe substrate detection sensor 20 in the vertical direction can bespecified by recognizing a vertical position of the end effector 7 inthe state in FIG. 7 and a vertical position of the end effector 7 in thestate in FIG. 8 . A vertical position of the end effector 7 in the statein FIG. 7 can be detected by switching an output signal of the substratedetection sensor 20 ON and OFF when the end effector 7 is raised orlowered.

On the other hand, a vertical position of the end effector 7 in thestate illustrated in FIG. 8 is detected using the method describedbelow.

First, as illustrated in FIG. 9 , the substrate S to be detected is heldby the end effector 7 and lifted slightly from the substrate supportingportion 22 of the substrate storing container. From the stateillustrated in FIG. 9 , the movable engagement portion 15 is retreatedso as to release the holding state of the substrate S by the substrateholding unit 13 as illustrated in FIG. 10 . From the state illustratedin FIG. 10 , the end effector 7 is slightly lowered by a predetermineddistance as illustrated in FIG. 11 . FIG. 11 illustrates the state thatthe substrate S is just placed on the substrate supporting portion 22,namely the state that the lower surface of the substrate S is positionedin the reference surface P0 of the end effector 7.

From the state illustrated in FIG. 11 , the substrate holding unit 13 isdriven so as to perform the substrate holding operation as illustratedin FIG. 12 . As the substrate S is in the position of the referencesurface P0 of the end effector 7 at this time, the substrate S is heldby the substrate holding unit 13. From the state illustrated in FIG. 12, the holding state of the substrate S by the substrate holding unit 13is released as illustrated in FIG. 13 . From the state illustrated inFIG. 13 , the end effector 7 is lowered by a predetermined distance asillustrated in FIG. 14 . Then, as the substrate S is supported by thesubstrate supporting portion 22 and is not moved, the lower surface ofthe substrate S is in a position slightly higher than the referencesurface P0 of the end effector 7, relatively.

From the state illustrated in FIG. 14 , the substrate holding unit 13 isdriven so as to perform the substrate holding operation as illustratedin FIG. 15 . At this time, the lower surface of the substrate S is in aposition higher than the reference surface P0 of the end effector 7 butlower than the upper surface 14A of the fixed engagement portion 14, andtherefore the substrate S is held by the substrate holding unit 13.

From the state illustrated in FIG. 15 , the holding state of thesubstrate S by the substrate holding unit 13 is released as illustratedin FIG. 16 , and the end effector 7 is lowered slightly by apredetermined distance as illustrated in FIG. 17 . In the stateillustrated in FIG. 17 , a vertical position of the lower surface of thesubstrate S is substantially matched with a vertical position of theupper surface 14A of the fixed engagement portion 14.

From the state illustrated in FIG. 17 , the substrate holding unit 13 isdriven so as to perform the substrate holding operation as illustratedin FIG. 18 . As a vertical position of the lower surface of thesubstrate S is substantially matched with a vertical position of theupper surface 14A of the fixed engagement portion 14 as stated above atthis time, the substrate S pressed by the movable engagement portion 15of the substrate holding unit 13 is displaced forward and goes on theupper surface 14A of the fixed engagement portion 14 as illustrated inFIG. 18 .

Here, a position of the plunger configuring the substrate holding unitis detected by the position sensor (holding state determination unit),and the position sensor detects that the plunger advances exceeding apredetermined position in the substrate holding state in the stateillustrated in FIG. 18 . Thereby, it can be detected that the substrateis in a non-holding state.

If a vertical position of the end effector 7 at a time point when thesubstrate holding state is switched into the substrate non-holding state(FIG. 18 ) is detected by a series of actions above, a position abovethe detection position by the distance D2 illustrated in FIG. 6 can bespecified as a position of the end effector 7 at a time point when thesubstrate S to be detected is held at the normal substrate holdingposition (position of reference surface P0) by the substrate holdingunit 15 (end effector position detection process).

Next, the separation distance D1 between the reference surface P0 of theend effector 7 and the substrate detection sensor 20 in the verticaldirection is specified based on a detection result in the detectionobject substrate detection process using the substrate detection sensor20 and a detection result in the end effector position detection process(separation distance specifying process). Namely, D1=D3−D2 isestablished.

Also, the robot controller 12 of the substrate conveying robot 1according to the embodiment detects a vertical position of the substrateS to be conveyed using the substrate detection sensor 20 based on theseparation distance D1 obtained in the separate distance specifyingprocess (conveying object substrate position detection process). Theelevating drive unit 8 is controlled based on a detection result by thesubstrate detection sensor 20 so as to hold the substrate S by thesubstrate holding unit 15.

As a variation of the embodiment above, the substrate holding unit canbe configured by a vacuum suction unit 23 for vacuum sucking thesubstrate S, and the holding state determination unit can be configuredby a vacuum sensor 24 detecting that the vacuum state is achieved by thevacuum suction unit 23 as illustrated in FIG. 19 .

As the fixed engagement portion (FIG. 2 , etc.) in the above-statedembodiment is not provided to the end effector 7 in the example, asuction surface according to the vacuum suction unit 23 corresponds tothe reference surface P0 of the end effector 7.

Even in the example, first, the lower surface of the substrate S to bedetected held by the substrate supporting portion 22 of the substratestoring container 21 is detected using the substrate detection sensor 20provided in the end effector 7 as illustrated in FIG. 20 (detectionobject substrate detection process) as well as the above-statedembodiment.

Also in the example, a vertical position of the end effector 7 at a timepoint when the substrate S to be detected is held by the vacuum suctionunit (substrate holding unit) 23 is detected as illustrated in FIG. 21(end effector position detection process) as well as the above-statedembodiment.

As the suction surface according to the vacuum suction unit 23corresponds to the reference surface P0 of the end effector in theexample, the substrate S to be detected is in the normal substrateholding position in the end effector 7 at a time point when adetermination result of the vacuum sensor (holding state determinationunit) 24 is switched. Therefore, as illustrated in FIG. 21 , theseparation distance D1 from the reference surface P0 of the end effector7 to the substrate detection sensor 20 in the vertical direction can bedirectly specified from a vertical position of the end effector 7 at atime point when the substrate S to be detected is held by the vacuumsuction unit (substrate holding unit) 23.

A method for detecting a vertical position of the end effector 7 at atime point when the substrate S to be detected is held by the vacuumsuction unit (substrate holding unit) 23 in the example will bedescribed referring to FIG. 22 to FIG. 24 .

First, as illustrated in FIG. 22 , the end effector 7 is positioned in aposition separate from the substrate S below the substrate S supportedby the substrate supporting portion 22 of the substrate storingcontainer 21. From the state illustrated in FIG. 22 , the end effector 7is slightly raised by a predetermined distance as illustrated in FIG. 23so as to drive the vacuum suction unit (substrate holding unit) 23. Asthe suction surface (reference surface P0) of the end effector 7 isseparated from the lower surface of the substrate S in the stateillustrated in FIG. 23 , the vacuum state is not achieved and the outputsignal of the vacuum sensor 24 is off.

From the state illustrated in FIG. 23 , the end effector 7 is slightlyraised by a predetermined distance as illustrated in FIG. 24 so as todrive the vacuum suction unit 23. As the suction surface (referencesurface P0) of the end effector 7 reaches the lower surface of thesubstrate S in the state illustrated in FIG. 24 , the vacuum state isachieved by the vacuum suction unit 23 and the output signal of thevacuum sensor 24 is turned on.

As mentioned above, a vertical position of the end effector 7 at a timepoint when holding the substrate S to be detected by the vacuum suctionunit (substrate holding unit) 23 can be detected by detecting a timepoint when the output signal of the vacuum sensor 24 is switched fromoff to on while bringing the end effector 7 close to the substrate S bya predetermined distance little by little.

FIG. 25 and FIG. 26 illustrate another variation of the above-statedembodiment, and the substrate detection sensor 20 is provided to thebase end portion of the end effector 7 not to the tip end portion of theend effector 7 in the example. The substrate detection sensor 20 in theexample is a reflection type optical sensor, for example, which detectsa position of the substrate S by detecting a light emitted from a lightemitting portion and reflected at a peripheral surface of the substrateS at a light receiving portion.

As the substrate detection sensor 20 is raised integrally with the endeffector 7 even in the example, the separation distance D1 between thereference surface P0 of the end effector 7 and the substrate detectionsensor 20 in the vertical direction can be specified as well as in theabove-stated embodiment or variation.

As stated above, according to the above-stated embodiments and therespective variations thereof, the substrate detection sensor (substratedetection unit) 20 for detecting a vertical position of the substrate Sis comprised. Therefore, the holding operation of the substrate S by thesubstrate conveying robot 1 can be performed with high accuracy bydetecting a vertical position of the substrate S to be conveyed usingthe substrate detection sensor 20 prior to the holding operation of thesubstrate S by the end effector 7.

For example, when a supporting structure (formed of quartz, and thelike) storing a plurality of substrates S is heated in a heat treatmentdevice in the semiconductor manufacturing process, the supportingstructure after treatment is sometimes deformed due to heat. Even insuch a case, the holding operation of the substrate S by the substrateconveying robot 1 can be performed with high accuracy by detecting avertical position of the substrate S stored in the supporting structureusing the substrate detection sensor 20 before taking the treatedsubstrate S out of the supporting structure by the substrate conveyingrobot 1.

Also, according to the above-stated embodiments and the respectivevariations thereof, the separation distance D1 of the substratedetection sensor 20 with respect to the reference surface P0 of the endeffector 7 in the vertical direction can be specified. Therefore, avertical position of the substrate S can be detected accurately usingthe substrate detection sensor 20 even when a position of the substratedetection sensor 20 with respect to the reference surface P0 of the endeffector 7 has a mounting error.

For example, when a wafer mapping sensor only for detecting the presenceand absence of a wafer is provided to an end effector, a position of thesensor with respect to the reference surface of the end effector has amounting error. However, even in the case, a vertical direction of thewafer can be detected accurately using the sensor by applying theabove-stated embodiments and the respective variations thereof.

Also, according to the above-stated embodiments and the respectivevariations thereof, the substrate detection sensor 20 is elevatedintegrally with the elevating operation of the end effector 7.Therefore, a relative position relation between the end effector 7 andthe substrate detection sensor 20 in the vertical direction is known,and an equipment configuration and arithmetic process can be simplercompared to the case when a separate substrate detection sensorindependent from the elevating operation of the end effector 7 is used.

Note that, in the invention, the mounting position of the substratedetection sensor does not necessarily need to be a position on the endeffector, and the substrate detection sensor may be mounted on a partwhich is elevated integrally with the elevating operation of the endeffector in the substrate conveying robot.

Also, in the present invention, a substrate to be detected in thedetection object substrate detection process and the end effectorposition detection process does not necessarily need to a substratesupported by a substrate supporting portion of a substrate storingcontainer such as a FOUP used in the actual substrate treatment process,and it may be supported by any substrate supporting portion.

Also, in the present invention, a performing order of the detectionobject substrate detection process and the end effector positiondetection process does not need to be considered. Namely, the endeffector position detection process may be performed after performingthe detection object substrate detection process, and vice versa.

Also, in the present invention, the reference surface of the endeffector does not necessarily need to be matched with the normalsubstrate holding position, and it may be in any position which can bespecified in the robot coordinate.

DESCRIPTION OF REFERENCE NUMERALS

-   1 . . . substrate conveying robot-   2 . . . base-   3 . . . rotary spindle-   4 . . . robot arms-   5 . . . first link member-   6 . . . second link member-   7 . . . end effector (hand)-   8 . . . drive source for elevating operation of rotary spindle    (elevating drive unit)-   9 . . . drive source for rotational operation of rotary spindle and    first link member (arm drive unit)-   10 . . . drive source of rotational operation of second link member    (arm drive unit)-   11 . . . drive source for rotational operation of end effector (arm    drive unit)-   12 . . . robot controller (robot control unit)-   13 . . . substrate holding unit-   14 . . . fixed engagement portion (substrate holding unit)-   14A . . . upper surface of fixed engagement portion-   15 . . . movable engagement portion (substrate holding unit)-   16 . . . plunger (substrate holding unit)-   17 . . . slender member (substrate holding unit)-   18 . . . step portion of fixed engagement portion-   19 . . . position sensor (holding state determination unit)-   20 . . . substrate detection sensor (substrate detection unit)-   21 . . . substrate storing container-   22 . . . substrate supporting portion of substrate storing container-   23 . . . vacuum suction unit (substrate holding unit)-   24 . . . vacuum sensor (holding state determination unit)-   L1 . . . first rotational axis line-   L2 . . . second rotational axis line-   L3 . . . third rotational axis line-   P0 . . . reference surface of end effector (normal holding position    of substrate)-   S . . . substrate

The invention claimed is:
 1. A substrate conveying robot comprising: arobot arm including an end effector having a substrate holder forholding a substrate; an arm drive unit comprising one or more motors fordriving the robot arm; an elevating drive unit comprising a motor forelevatingly driving the end effector; a robot controller for controllingthe arm drive unit, the elevating drive unit, and the substrate holder;and a substrate detection unit for detecting a vertical position of thesubstrate, the substrate detection unit comprising a substrate detectionsensor which elevates coordinately with an elevating operation of theend effector, wherein the robot controller is configured to control theelevating drive unit for raising or lowering the end effector so as todetect the substrate by the substrate detection sensor and specify aseparation distance between a reference surface of the end effector andthe substrate detection sensor in a vertical direction based on avertical position of the end effector at a detection time point when thesubstrate, which is stored in a container, is detected by the substratedetection sensor and a vertical position of the end effector at a timepoint when the substrate, which is stored in the container, is held bythe substrate holder at a normal substrate holding position, the normalsubstrate holding position being a position where the substrate isnormally held by the substrate holder during a normal operation of thesubstrate conveying robot, wherein the reference surface of the endeffector is matched with the normal substrate holding position, andwherein the substrate detection sensor is provided to the end effector.2. The substrate conveying robot according to claim 1, furthercomprising a position sensor for determining whether the substrate isheld by the substrate holder or not.
 3. The substrate conveying robotaccording to claim 2, wherein the robot controller is configured todetect a time point when a determination result of the position sensoris switched while raising or lowering the end effector by the elevatingdrive unit by a predetermined distance each in order to detect avertical position of the end effector at a time point when the substrateis held by the substrate holder at the normal substrate holdingposition.
 4. The substrate conveying robot according to claim 2, whereinthe substrate holder has a vacuum for vacuum sucking the substrate, andwherein the position sensor has a vacuum sensor which detects that avacuum state is achieved by the vacuum.
 5. The substrate conveying robotaccording to claim 1, wherein the end effector is configured to beelevated integrally with the robot arm, and wherein the elevating driveunit is configured to elevate the end effector by elevating the robotarm.
 6. The substrate conveying robot according to claim 1, wherein therobot controller is configured to detect a vertical position of thesubstrate to be conveyed by the substrate detection sensor and controlthe elevating drive unit based on a detection result so as to hold thesubstrate by the substrate holder.
 7. An operation method of a substrateconveying robot comprising a robot arm to which an end effector having asubstrate holder for holding a substrate is provided, comprising: adetection object substrate detection process of detecting the substrateto be detected using a substrate detection sensor which elevatescoordinately with an elevating operation of the end effector; an endeffector position detection process of detecting a vertical position ofthe end effector at a time point when the substrate to be detected isheld at a normal substrate holding position by the substrate holder, thenormal substrate holding position being a position where the substrateis normally held by the substrate holder during a normal operation ofthe substrate conveying robot; and a separation distance specifyingprocess of specifying a separation distance between a reference surfaceof the end effector and the substrate detection sensor in a verticaldirection based on a detection result, which includes a verticalposition of the end effector at a detection time point when thesubstrate, which is stored in a container, is detected by the substratedetection sensor, in the detection object substrate detection processand a detection result, which includes the vertical position of the endeffector at the time point when the substrate, which is stored in thecontainer, is held by the substrate holder at the normal substrateholding position, in the end effector position detection process,wherein the reference surface of the end effector is matched with thenormal substrate holding position, and wherein the substrate detectionsensor is provided to the end effector.
 8. The operation method of asubstrate conveying robot according to claim 7, wherein the substrateconveying robot further has a position sensor for determining whetherthe substrate is held by the substrate holder or not, and wherein, inthe end effector position detection process, a time point when adetermination result of the position sensor is switched is detectedwhile raising or lowering the end effector by a predetermined distanceeach.
 9. The operation method of a substrate conveying robot accordingto claim 8, wherein the substrate to be detected is at the normalsubstrate holding position at a time point when a determination resultof the position sensor is switched.
 10. The operation method of asubstrate conveying robot according to claim 7, further comprising aconveying object substrate position detection process of detecting avertical position of the substrate to be conveyed using the substratedetection sensor based on the separation distance obtained in theseparation distance specifying process.